After five years of appearing in satellite images, swirling spots in the Baltic Sea have an explanation. The substance that appears on the surface of the water in the Bay of Gdansk, Poland, is pollen from pine trees in the region.
Although the spots are visible to the naked eye, they become clearer through the composition of satellite images in false color — a technique that uses shades different from the real ones to highlight certain elements that one wants to analyze. It was already known how the spiral shape arises — the movement of waves and sea currents, influenced by winds — but what, in fact, the substance was remained a mystery.
The first suspicion was that it was marine mucilage, or marine mucus, a viscous material formed by plankton, organic matter and minerals. A scientific paper earlier this year, however, revealed that the substance’s reflective properties were more similar to pine pollen. A new study confirmed the hypothesis by collecting samples and analyzing the particles in the laboratory.
More than 55% of the trees in Poland are pines, which means that 30% of its territory is covered by these species. Now knowing what it was, scientists were able to find in images from the past another 14 appearances of the spots between 2000 and 2021, also noting their gradual increase in the period and an appearance earlier and earlier in the year.
The observations are consistent with a global trend of increased pollen levels, reported in other studies as a result of climate change — NASA claims that additional carbon in the atmosphere allows plants to produce more of this substance.
Those responsible for the study say that, due to the high amount of organic material agglomerating on the surface of the ocean in this way, future research needs to assess the impact of pollen patches on the marine ecosystem. In addition, public health experts say the rising trend in pollen can affect people with allergies.
Source: Remote Sensing of Environment Via: Live Science, NASA Earth Observatory
